ANNULÉ - The same, yet different: gene expression variability between genetically identical plants
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Résumé
A fundamental question in biology is how gene expression is regulated to give rise to a given phenotype. However, transcriptional variability, or noise, is rarely explored and could strongly influence the relationship between genotype and phenotype. It is known in unicellular organisms that gene expression is often noisy rather than uniform with different individuals showing variable gene expression behaviours. Such transcriptional variability has been proposed to be beneficial when environmental conditions are unpredictable. However, little is known about transcriptional variability in multicellular organisms.
I am analysing gene expression variability between individuals in Arabidopsis thaliana, and how this could be of importance for the response to environment. Using transcriptomic approaches we characterised, over a 24 hours time-course, the level of gene expression variability between individuals growing in controlled conditions. We identified hundreds of genes that exhibit high inter-individual variability in gene expression and found that many are involved in the response to environment. We also identified factors that might be facilitating gene expression variability, such as gene size, the number of transcription factors regulating a gene and the chromatin environment.
In order to define the relevance of this gene expression variability, I am now exploring its regulation and consequences in the context of nitrate nutrition in plants. The response to nitrate is a good model for such study, as not only have I observed that some of the main factors of the response to nitrate show high inter-individual gene expression variability, but nitrate availability is also spatially and temporally heterogeneous in the wild.
These results will bring a new light into the impact of transcriptional variability in gene expression regulation in plants.